Diagnostic instrument



FIG. 1 is a rear, right-side, top perspective view of the diagnostic instrument, showing the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a right-side elevational view thereof;

FIG. 5 is a left-side elevational view thereof;

FIG. 6 is a front, right-side, top perspective view thereof; and,

FIG. 7 is a front, bottom, right-side perspective view thereof.

The broken lines depict parts of the diagnostic instrument that form no part of the claimed design. 

CLAIM The ornamental design for a diagnostic instrument, as shown and described. 